Furnace igniter



June 7 1927. F. P. TERRY 1,631,348

FURNACE IGNITER Filed Aug. 10. 1925 INYENTOR FREDERICK P ERRY Patented June 7, 1927.

UNITED STATES FREDERICK I. TERRY, OF ALAMEDA, CALIFORNIA.

FURNACE IGNITER.

Application filed August 10, 1925. Serial No. 49,491.

This invention relates to ignition systems 1nd is particularly applicable to furnaces for heating purposes.

Prior to my invention gas furnaces have been provided with electrical ignition means and with a fuel valve having electrically controlled operating mechanism. The circuit of this operating mechanism was opened and closed by a switch, located at a point comparatively remote from the furnace. This switch was usually of the push button type, and when it was desired to place the furnace in operation, this switch was pressed and released. By pressing the switch a circuit was closed which caused the valve to open and which created a spark adjacent the burner of the furnace to ignite the fuel. The duration of the ignition spark, however, was only for the period during which the circuit was maintained closed by the operator pressing the button. In some cases the operator would not hold the circuit closed for a time sufficient to cause ignition of the fuel. This had very disastrous results as it caused the furnace and fines to be filled with unburned gas which if ignited caused explosions.

It is the principal object of the present invention to overcome this disadvantage in prior devices by providing an ignition system wherein the ignition spark will endure for a predetermined length of time, regardless of how long the operator maintains the valve operating circuit closed.

In carrying out this object, I provide a main circuit for actuating the control valve mechanism, which circuit may be closed from a point remote from the furnace. I also provide an ignition circuit which will he closed simultaneously with the main circuit, but which will be automatically opened independently of the main circuit after the lapse of a predetermined interval of time. In this way I insure that the igniting spark will be of sufficient duration to ignite the fuel delivered to the burner.

One form which the invention may assume is exemplified in the following description and illustrated by way of example in the accompanying drawings, in which:

Fig. 1 is a diagrammatical view disclosing my improved system.

Fig. 2 is a view in elevation and partly in section disclosing the mechanism by which I close and open the ignition system.

Referring more particularly to the accompanying drawings, 10 indicates the fuel control valve of a furnace or other apparatus to which my improved ignition system is applicable. This valve may be of any type having a rotatable valve controlling the communication between a fuel supply pipe 11 and a pipe 12 for conveying the fuel to the burners of the furnace. Valves of this type are in common use and for this reason it is merely diagrammatically illustrated. It should be stated, however, that the valve member is formed with three ports of different area so that three different quantities of fuel may be delivered to the pipe 19.. That is to say, the valve may be entirely closed and upon three successive quarter revolutions thereof its different ports will successively register with a port communicating with the pipe 12. Upon the fourth quarter revolution, the valve will again entirely shut off communication between the pipes 11 and 12.

To operate the valve 10, it is fitted with a rotatable shaft 14 upon which a gear 15 is loosely mounted. The teeth of this gear mesh with rack teeth formed on the core 16 of a solenoid magnet 17. When a circuit is completed through the solenoid the core 16 will move axially a distance sufficient to rotate the gear 15 one-quarter of a revolution. This motion is transmitted to the shaft through a pawl 18 on the gear and a ratchet 19 fixed onv the shaft. The moment that the circuit through the solenoid is broken, the core 16 and the gear 15 return to normal position but the shaft remains stationary.

One side of the solenoid is grounded. The other side is led to a push button switch 20 and thence to a transformer 21 which may derive current from any desired source, The transformer is provided for the reason, that most buildings equipped with furnaces in connection with which. my system will be employed, are provided with 110 volt circuits. As my apparatus uses less voltage than this, a transformer to cut down the voltage is employed.

It is intended that when the valve is moved from closed to its first open position that a spark be created adjacent the furnace burners simultaneously with the opening of the valve to ignite the fuel delivered through the pipe 12. For this purpose, one side of the transformer 21 is connected with a spark coil 22 One terminal of this coil is led to an ignition'plug 23 the other side" of which is grounded. The circuit of this plug is normally open and is controlled by a switch 24. This switch comprises a movable spring contact arm 25 and a stationary arm 26 which is connected to the other terminal of the spark coil 22. a circuit from the transformer through the ignition plug is completed resulting in a sparkfor igniting the fuel.

For operating the switchQl, 1 provide astationary piston 28 upon wlnch a cylinder 29 is reciprocably mounted. The upper end of tl'iiscylinder is closed and is titted with a ball check valve 30 which permits air to be drawn in between the upper ends of the piston andcylinder when the latter is raised relative to thepiston. Downward movement of the cylinder causes the air thus confined to be expelled between the sides of the piston and cylinder. As gravity is the only force providedfor lowering the cylinder, the air will expel very slowly and retard the downward movement of the cylinder so that its down stroke will consume a predetermined time period.

The lower end of the cylinder 29 abuts against the contact arm 25 and normally holds the switch 24 open. When the cylinder is elevated the arm 25 instantly contacts with the arm 26'to close the switchand closes the circuit through the ignition plug. As soon as the cylinc er is elevated it is released and permitted to slowly move downwardly to its normal position. Just prior to reachingthe lower end of its travel, the cylinder will engage the arm-25 and open the switch 24 and thus open the circuit through the ignition plug 23. The retarded action of the cylinder and the switch 24 causes the spark t'o'contimie a predetermined length of time after the valve has opened and the circuit through the solenoid discontinued. This insures that the fuel delivered to the'furnace will have ample opportunity to ignite.

It should he stated that the cylinder is elevated simultaneously with the opening of thevalve. This is accomplished by fitting the valve shaft with a cam 30 which engages a push rod 3,1 which in turn engages a lateral projection on" the cylinder. Dur-' ing the first quarter rcvolution'of' the valve shaft which is caused by a'circuit being completed through the solenoid as described, the cam' raises and lowers the push rod 31 to elevate the cylinder. The instant the' rod 31 moves upwardly, thecyli'nder is elevated sut'liciently to cause the contact arm 25-to contact with the arm26'and close the circuit through the ignition plug. This circuit will remain closed until-the cylinder moves down: wardly an amount necessary tobrea'k the contact between the arms 25 and 26 and thus open the-ignition circuit.

lVhen the switch 2st is closed,.

It should be stated that the valve controlling circuitis controlled by a push button type of switch as it is only necessary to close the circuit through the solenoid for an instantin-order toopen the valve. However, the ignition circuit remains closed for a period after the valve opening circuit is open due to the delayed action of the cylinder which operates the switch 24;.

To indicate the position of the alve, two lamps 31, and 32 are provided. One side of each lamp connects with. the lead which connects one side of the main switch with the transforn'ier. The other side of the lamps are connected to independent switch plates t3" and These plates are adapted to be cngaged by protuherances on the valve shaft as the latter is rotated. For example, when the main switch is closed to move the valve from closed to first open position the circuit will be completed through both of the lamps 31 and 32 because both of'the plates 33 and 34- will be electrically connected with the valve shaft to complete the circuits. When the main switch is closed a second time to place the valve in second open position. only the circuit tl'i'rough the lamp 32 will be completed due to the position of the protuberances which are adapted to contact with the'plat'e 33. Likewise when the valve is turned to third positioru the projection on the shaft will engage the plate 3%, thus closingthe circuit through the light 31 and opening that through the light 32. Thus the operator may by glancing at the two indicator lights 31. and 32 be advised as to the position of the valve.

ll hen the main switch is depressed for the fmu'th time, the valve will be closed and the circuits through both lights 3l'and 39, will be opened indicating that the valve is closed.

In actual operation of the device; it will be assumed-that th'e'valve is in closed position. lVhen the main s itch is depressed and'releas'ed a circuit will have been closed through the solenoid for a suitieientperiod to elevate the core- 16' thereof and impart a quarter revolution to the valve shaft 1 L through the medium of the gear 15, the pawl and ratchet Band 19. During'this quarter revolution, the cam'30 will reciprocate'the pushrcd 31 to elevate the cylinder 29. As previously described, the elevation of the cylinder 29'permits the contact arm 25 to engage the arm 26and complete the ignition circuit through the ignition plug 23. thus causingthe spark to ignite the fuel admitted to the barrier of the furnace through the valve 10.

Simult'aneouslywith the turning of the valve shaft, circuits will be completed. throughtheswitches'33' and 34 to light the lamps 31' andSQ'indicatingthat the-valve is in first openposition.

As soon as the cylinder is raised it is released by the push rod 31 and allowed to travel slowly downwardly. .The period of its travel back down to normal position determines the length. of time during which the spark is continued at the ignition plug for ignition purposes. As it reaches the lower end of its downward stroke, the cylinder contacts with the contact arm 25 and, as described, opens the switch 24, thus breaking the circuit through the ignition plug 23.

It should be stated that the time interval desired for a continued spark may be any length desired and is determined by the construction of the cylinder 29 and the piston 28. It is to be understood that other means may be substituted for the cylinder 29 and the piston 28 for causing retarded opening of the ignition circuit and for delaying thereof for a predetermined period after the valve operating circuit has been discontinned.

The second time the main switch is closed, the valve is rotated a second quarter revolution to place it in second open position which will be indicated by the lights 31 and 32 as described. Likewise the third and fourth successive times the main switch is closed will operate the valve to place it in third open position and close it. ,These positions of the valve will be likewise indicated by the lights 31 and 32. It should be stated, however, that the second, third and fourth operations of the switch will affect only the valve-operating circuit, the ignition circuit being closed and opened on every first closing of the valve operating circuit.

From the foregoing it is obvious that the system I have provided will prevent the fuel valve from being opened and improper ignition supplied for igniting the fuel. Prior to my invention the ignition circuit was closed only during the period that the valve controlling circuit was closed. This length of time depended upon how long the operator maintained the main switch depressed. Tlherefore, the time of duration of the spark was sometimes insufiicient to ignite the fuel, thereby permitting the furnace to fill with unburned gases. By my invention, however, the length of the duration of the spark is constant regardless of the length of time that the valve operating circuit is closed. This insures that the fuel will be ignited.

\Vhile I have shown the preferred form of my invention, it to be understood that various changes in its construction may be made by those'skilled in the art without departing from the spirit of the invention as defined. in the appended claims.

Having thus described my invention, what i claim and desire to secure by Letters Patent is:

1. A. furnace ignition system including a fuel control valve controlling the supply of fuel delivered to the burners of a furnace, electrically actuated means for operating said control valve, a normally open main electrical circuit for operating said means, said valve being normally closed and adapted to be opened to progressively decreasing degrees in successive steps, each step occurring upon the closing and opening of the main circuit whereby by successively closing and opening said main circuit said valve will be advanced through its cycle of operation, a second circuit for creating an ignition spark to ignite fuel delivered to the burners of the furnace, means actuated by the closing of the main circuit at the commencement of the cycle of operation of the valve for closing the second circuit, means for automatically opening the second circuit independently of the main circuit and after a predetermined time period has elapsed, further opening and closing of the main circuit during the remaining portion of the cycle of operation of the valve unaffecting the second circuit.

2. A furnace ignition system including a normally closed fuel control valve for supplying fuel to the burners of a furnace, said valve adapted to be operated step by step through a certain cycle from closed position through open positions to a closed position, electrically actuated means for operating said valve step by step. a normally opened main electrical circuit for said means, each closing and opening of said main circuit moving said valve through one step of its cycle of operation, a normally opened ignition circuit for creating an ignition spark for igniting the fuel delivered to the burners of the furnace, means actuated by the closing of the main circuit during the first step of the cycle of operation of the valve for closing the second circuit, means for maintaining said second circuit closed for a predetermined length of time and then opening it, the closing of said second circuit being effected by closing the main circuit when advancing the valve through its first step of its cycle of operation only.

FREDERICK P. TERB Y. 

